The common use of tablets, smartphones, and smartwatches, which are today equipped with HD digital cameras and touchscreen electronic visual displays and sensors, have enabled software developers to use new algorithms and methods for the creation of medical apps. These apps can perform tests for diagnosing a large variety of diseases, including skin cancer, cardiovascular disorders, and diabetes. In this paper, the main focus is given on the use of smartphone digital cameras for testing and diagnosing dermatological diseases, while comparisons are made with previous research work on apps for measuring blood pressure, diabetes, and ocular anomalies. The research aims to identify the areas for converging the capabilities of mobile apps by integrating their data into the Cloud-based data warehouses or Big Data repositories of online hospital information systems. As such, it will be possible to improve the performance of diverse medical apps that are used in the testing, diagnosis, and treatment of a multitude of diseases. Thanks to the similarities in the tools, methods, and parameters for the measurement and diagnosis of various types of medical disorders, the possibility of creating a unique multipurpose medical app is continuously increasing. Another area of focus is the architecture of Cloud-based data warehouses or Big Data repositories, through which these apps can exchange data with online hospital information systems and therefore be used for aiding physicians in making more accurate decisions.